Field of the Invention
The present invention relates to the field of semiconductor emitters and detectors.
Related Art
Surface defects dominate the behavior of minority carriers in semiconductors and place a strong limit on the performance. This is especially true in optoelectronic devices whose behavior is completely dominated by minority carriers. One of the major implications is that the photoluminescence quantum yield (a figure that dictates the efficiency of devices such as light emitting diodes, lasers, and solar cells) is extremely low in materials that contain a large number of surface defects.
This problem is currently addressed in Silicon by using hydrofluoric (HF) treatment for surface passivation. However, HF treatment is unstable and the reduction in surface recombination velocity after treatment only lasts for 1-2 minutes.
Here we utilize chemical treatments using an organic super acid molecule to passivate and/or repair the surface defects in various semiconductor systems.
Enhancing the photoluminescence quantum yield (QY) in 2D transition metal dichalcogenide (TMDCs) to values near 100% such as MoS2, WS2, MoSe2, WSe2, MoTe2, WTe2 enables the fabrication of high performance optoelectronic devices (including but not limited to light emitting diodes, lasers, and solar cells).
Bistriflimide, systematically known as bis(trifluoromethane)sulfonimide and colloquially as TFSI, is a non-coordinating anion with the chemical formula [(CF3SO2)2N]−. In use with silicon, TFSI treatment can be used as a surface passivation treatment for devices which can dramatically reduce the surface recombination velocity (SRV). For example in use in solar cells this can have a dramatic improvement on the Voc of the device. The air-stable room-temperature reduction of the SRV by TFSI also permits the bulk lifetime to be easily measured.
By chemical treatment, the luminescence efficiency of monolayer MoS2 is enhanced from 1% to >95% enabling high performance chalcogenide optoelectronics.